Kabushiki Kaisha Toshiba

Mayumi Morizuka

Takashi Kawakubo

Kazuhide Abe

Yasuhiro Isobe

Tadahiro Sasaki

Yoshiaki Kitaura

Kazuhiko Itaya

Hiroshi Yoshida

Kentaro Ikeda

Keiichi Yamaguchi

Ryoichi Ohara

Takaaki Yasumoto

Kenya Sano

Nobuyuki Itoh

Yoshiharu Takada

Atsushi Kameyama

Naoko Yanase

Ryuichi Fujimoto

Kazuya Nishihori

Masami Nagaoka

Hirotsugu Wakimoto

Tooru Kozu

Takeshi Ookubo

A nitride semiconductor device includes a first semiconductor layer, a second semiconductor layer, a third semiconductor layer including a nitride semiconductor provided between the first semiconductor layer and the second semiconductor layer, the third semiconductor layer being contact with the first semiconductor layer and the second semiconductor layer, and a concentration of acceptor type impurity in the third semiconductor layer is higher than that in the first semiconductor layer and the second semiconductor layer, and including a source electrode and a drain electrode, a gate electrode, a first insulating layer, and a fourth semiconductor layer and a fifth semiconductor layer, wherein the nitride semiconductor device satisfying the following formula 0&#x3c;d&#x3c;2[(2&#x2208;E)/(qN)].

Nitride semiconductor device

A semiconductor device includes a first semiconductor layer, a second semiconductor layer, a third semiconductor layer, a first electrode, a second electrode, a control electrode, and a third electrode. The second semiconductor layer is provided on the first semiconductor layer and has a band gap narrower than that of the first semiconductor layer. The second semiconductor layer includes a first portion and a second portion which is provided together with the first portion and contains an activated acceptor. The third semiconductor layer is provided on the first portion and has a band gap wider than or equal to the band gap of the second semiconductor layer. The first and the second electrodes are provided on the third semiconductor layer. The control electrode is provided between the first electrode and the second electrode. The third electrode is provided on the second portion.

High electron mobility transistor (HEMT) capable of absorbing a stored hole more efficiently and method for manufacturing the same

According to an embodiment, a nitride semiconductor Schottky diode includes a first layer including a first nitride semiconductor and a second layer provided on the first layer and including a second nitride semiconductor having a wider band gap than the first nitride semiconductor. The diode also includes an ohmic electrode provided on the second layer and a Schottky electrode provided on the second layer. The second layer includes a region containing an acceptor in the vicinity of the Schottky electrode between the Schottky electrode and the ohmic electrode.

Nitride semiconductor Schottky diode and method for manufacturing same

A semiconductor device that can more efficiently absorb a stored hole includes a first semiconductor layer, a second semiconductor layer, a third semiconductor layer, a first electrode, a second electrode, a control electrode, and a third electrode. The second semiconductor layer is provided on the first semiconductor layer and has a band gap narrower than that of the first semiconductor layer. The second semiconductor layer includes a first portion and a second portion which is provided together with the first portion and contains an activated acceptor. The third semiconductor layer is provided on the first portion and has a band gap wider than or equal to the band gap of the second semiconductor layer. The first and the second electrodes are provided on the third semiconductor layer. The control electrode is provided between the first electrode and the second electrode. The third electrode is provided on the second portion.

High electron mobility transistor (HEMT) capable of absorbing a stored hole more efficiently

According to an embodiment, a semiconductor device includes a first layer including a first nitride semiconductor, a second layer provided on the first layer and including a second nitride semiconductor having a wider bandgap than the first nitride semiconductor. The device also includes a source electrode and a drain electrode provided on the second layer; and a gate electrode provided on the second layer and located between the source electrode and the drain electrode. The second layer includes a first region between the gate electrode and the drain electrode, the first region being selectively provided in a surface of the second layer and contains fluorine. A concentration of fluorine in the first region is higher than a concentration of fluorine in a portion underneath the gate electrode in the second layer.

Semiconductor device and method for manufacturing same

A semiconductor device of an embodiment includes: a first semiconductor layer made of AlGaN (0&#x3c;x&#x3c;1) or InAlN (0&#x2266;y&#x2266;1); a first semiconductor region, an insulating film, and an anode electrode that are formed on the same plane of the first semiconductor layer, and are made of undoped, n-type, or p-type GaN; and a cathode electrode formed on the first semiconductor region. In this semiconductor device, the first semiconductor region, the insulating film, and the anode electrode are joined to the first semiconductor layer. The insulating film is joined to the first semiconductor layer between the first semiconductor region and the anode electrode. The junction between the anode electrode and the first semiconductor layer is an ohmic junction. The junction between the cathode electrode and the first semiconductor region is an ohmic junction.

Semiconductor device

A manufacturing method is provided for a voltage controlled oscillator comprising an thin film BAW resonator and a variable capacitor element. The thin film BAW resonator includes an anchor section formed on a Si substrate, a lower electrode supported on the anchor section and positioned to face the Si substrate, a first piezoelectric film formed on the lower electrode, and an upper electrode formed on the first piezoelectric film. The variable capacitor element includes a stationary electrode formed on a Si substrate, an anchor section formed on the Si substrate, a first electrode supported on the anchor section and positioned to face the Si substrate, a second piezoelectric film formed on the first electrode, and a second electrode formed on the second piezoelectric film.

Method of manufacturing a voltage controlled oscillator

A voltage controlled oscillator includes a resonator configured to resonate with an initial oscillation frequency during starting period of oscillation and a steady oscillation frequency during a steady state oscillation. The resonator includes a film bulk acoustic resonator having a series resonance frequency higher than the steady oscillation frequency. A negative resistance circuit configured to drive the resonator, has a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.

Voltage controlled oscillator, frequency synthesizer and communication apparatus

The present invention provides a voltage controlled oscillator comprising an thin film BAW resonator and a variable capacitor element. The thin film BAW resonator includes an anchor section formed on a Si substrate, a lower electrode supported on the anchor section and positioned to face the Si substrate, a first piezoelectric film formed on the lower electrode, and an upper electrode formed on the first piezoelectric film. On the other hand, the variable capacitor element includes a stationary electrode formed on a Si substrate, an anchor section formed on the Si substrate, a first electrode supported on the anchor section and positioned to face the Si substrate, a second piezoelectric film formed on the first electrode, and a second electrode formed on the second piezoelectric film.

Voltage controlled oscillator

A high electron mobility transistor comprises a GaN-based electron accumulation layer formed on a substrate, an electron supply layer formed on the electron accumulation layer, a source electrode and a drain electrode formed on the electron supply layer and spaced from each other, a gate electrode formed on the electron supply layer between the source and drain electrodes, and a hole absorption electrode formed on the electron accumulation layer so as to be substantially spaced from the electron supply layer. Since the hole absorption electrode is formed on the electron absorption layer in order to prevent holes generated by impact ionization from being accumulated on the electron accumulation layer, a kink phenomenon is prevented. Good drain-current/voltage characteristics are therefore obtained. A high power/high electron mobility transistor is provided with a high power-added efficiency and good linearity.

High electron mobility transistor and method of manufacturing the same

A method of manufacturing a high electron mobility transistor, comprising laminating an electron accumulation layer and an electron supply layer successively on a substrate; selectively removing the electron supply layer to isolate an element region; forming a source and a drain electrode on the electron supply layer of the isolated element region; and forming a hole absorption electrode on the electron accumulation layer exposed by the selective removal of the electron supply layer, and simultaneously forming a gate electrode on the electron supply layer of the isolated element region.

Method of manufacturing a high electron mobility transistor

High electron mobility transistor

According to this invention, a group III nitride inverted high electron mobility transistor, and a power amplifier using the same are provided. A transistor and power amplifier according to this invention are characterized in that the lattice constant of a bulk of a donor layer is larger than that of an underlayer containing a group III nitride compound semiconductor material, or the donor layer is made of impurity-doped Al Ga N, the underlayer is made of undoped Al Ga N, and x and y satisfy an inequality 0&lE;y<x&lE;1.

High electron mobility transistor and power amplifier

A MESFET of a GaAs semiconductor device having a p-pocket LDD structure is used for a high-frequency power amplifier of a mobile communication device, in order to decrease current consumption and to increase the continuous operating time of a battery. The high-frequency power amplifier is provided with a gate-bias adjusting feedback element between the drain and gate of the MESFET. Thus, even if there is a great difference between the filled and terminated potentials of the discharge voltage of the battery for supplying electric power to the amplifier, electric power can be supplied near the terminated potential for a long time, so that the mobile communication device can be continuously used for a long time.

Growing community of inventors

Kawasaki, Japan

Mayumi Morizuka